Letters in Organic Chemistry, Volume 1, No. 3, 2004
Contents
Influence of the Nature of Low Valent Titanium Reagents
in McMurry Olefination: Stereoselective Synthesis of Symmetrical and
Unsymmetrical Hydroxystilbenes Pp.203-207
Catalytic Enantioselective Addition of Me2Zn
to Aromatic Aldehydes Promoted by New Modular Thiophene-Oxazoline Ligands Pp.208-211
P.
G. Cozzi and M. Locatelli
Yb(OTf)3 and ZrCl4 Mediated
Rearrangement of Alkoxybenzyl Allyl Ethers into Aldehydes#Pp.212-214
Palakodety
Radha Krishna, Ch. Govardhan Reddy and G. V. M. Sharma
Synthesis of Alicyclic β-lactams via the Ugi
Reaction on a Solid Support Pp.215-220
S.
Gedey, J. Van der Eycken and F. Fulop
Intramolecular Azide Cycloaddition enroute to the New
Pyrrolo[2,1-c][1,2,3] triazolo[1,5-a][1,4]benzodiazepine Skeleton
Pp.221-223
G.
Broggini, I. De Marchi, M. Martinelli, G. Paladino and A. Penoni
Re-Evaluation of a Solid-Phase Hydantoin Synthesis Pp.224-226
Jesus
Vazquez, Miriam Royo and Fernando Albericio
Multivalent Recognition of Flavin Derivatives Using
Polymer Scaffolds Pp.227-230
Joseph
B. Carroll, Mark Gray, Kevin M. Bardon, Hiroshi Nakade and Vincent M. Rotello
Synthesis of Luminescent N-Arylcarbazoles by
Copper Bronze-Mediated Reaction Pp.231-237
M.
Martinez-Palau, E. Perea, F. Lopez-Calahorra and D. Velasco
Synthesis of Boronated Alkoxyphenylalanines Pp.238-245
A.
Wolan, A. Laczynska, Z. Rafinski and M. Zaidlewicz
Synthesis of Enol Adenosine 5'-Phosphate Derivatives by
the Perkow Reaction of a Silylated Adenosine 5'-Phosphonate Derivative with
α-Halo Ketones Pp.246-248
Tomohisa
Moriguchi, Kazuhisa Okada, Kohji Seio and Mitsuo Sekine
Chiral Linker 1. A Novel Chiral Auxiliary Derived from m-Hydrobenzoin
as Enantiomerically Pure Linker for Solid Phase Organic Chemistry Pp.249-253
P.
Gaertner, C. Schuster and M. Knollmueller
Chemoenzymatic Approach to a (R)-3,
4-Diaminobutanoic Acid Derivative with a Suitable Orthogonal Protection for
Solid Phase Peptide Synthesis Pp.254-256
Monica
Lopez-Garcia, Ignacio Alfonso and Vicente Gotor
Further Advances in the Synthesis of
α,β’-Difunctionalised Pyrroles Pp.257-260
Severine
Hebbe and Luc Dechoux
Efficient Synthesis of Octahydro-5H-Dibenz[b,f]azepin-10-one
Derivatives by an Easy Two-Step Route from Available 2-Carbethoxymethyl
Cyclohexanone and Anilines Pp.261-263
Alirio
Palma, Jacqueline Jaimes Barajas, Vladimir V. Kouznetsov, Elena Stashenko, Ali
Bahsas and Juan Amaro-Luis
Mild and Most Efficient Silylcyanation of Aldehydes
Catalyzed by Cesium Fluoride Pp.264-267
Sung
Soo Kim and Dae Ho Song
Highly Diastereoselective Methylation of Five-Ring N,O-Acetals
Pp.268-270
Martin
Brunner, Thomas Straub, Pauli Saarenketo, Kari Rissanen and Ari M. P. Koskinen
The First Dye-sensitized Photooxygenation of 2-(C-glycosyl)furans.
One-Pot Stereoselective Approach to New Carbohydrate Derivatives Pp.271-275
Flavio
Cermola, M. Rosaria Iesce and Stefania Montella
A Facile Synthesis of Dibenzylated p-tert-Butylcalix[4]Crowns
Under Non-Diluted Reaction Conditions Pp.276-279
Hirohito
Tsue, Tatsuya Takimoto, Rui Tamura, Chieko Kikuchi and Shunitz Tanaka
Collapse and Self-Reconstruction of Mesoscopic Architectures
of Supramolecular J Aggregates in Solution: From Strings to Tubular Rods Pp.280-287
Hiroshi
Yao, Chris A. Michaels, Stephan J. Stranick, Takeshi Isohashi and Keisaku
Kimura
Abstracts
[Back to top] Influence of the Nature of Low Valent Titanium
Reagents in McMurry Olefination: Stereoselective Synthesis of Symmetrical and
Unsymmetrical Hydroxystilbenes
Narayan V. Mayekar, Subrata Chattopadhyay and Sandip K. Nayak
Intramolecular reductive deoxygenation of ethylenedioxy tethered symmetrical and unsymmetrical aromatic bis(ketone) ethers with the low-valent titanium (LVT) reagent (TiCl4-Zn-DME) yielded the corresponding cyclic stilbenes with excellent Z-selectivity. On the other hand, coupling of the aldehydic tethered ethers proceeded with high E-selectivity with the LVT reagent (TiCl3/Li/KCl (2.0 eq.) /THF). Dealkylation of the cyclic stilbenes furnished the geometrically pure hydroxystilbenes.
[Back to top] Catalytic Enantioselective Addition of Me2Zn
to Aromatic Aldehydes Promoted by New Modular Thiophene-Oxazoline Ligands
P.
G. Cozzi and M. Locatelli
A small library of aryl and dialkyl 3-hydroxy thiophene 2-oxazolines was simply prepared by direct and selective metalation of 4-tertbutyl-2-(thiophene-2-yl)-4,5-dihidrooxazole and its successive reaction with aromatic and aliphatic ketones. The ligand 7h was able to promote the addition of Me2Zn to aromatic aldehydes with good enantioselectivity (up to 92 % ee).
[Back to top] Yb(OTf)3 and ZrCl4 Mediated
Rearrangement of Alkoxybenzyl Allyl Ethers into Aldehydes#
Palakodety
Radha Krishna, Ch. Govardhan Reddy and G. V. M. Sharma
Lewis acid mediated rearrangement of alkoxybenzyl allyl ethers into aldehydes in moderate to good yields, catalysed either by Yb(OTf)3 or ZrCl4 is reported. The ZrCl4 catalysed transformation offers mild and easily adaptable clean reaction conditions and good yields of the products. Additionally, ZrCl4 catalysed rearrangement under solvent free conditions is an advantageous modification.
[Back to top] Synthesis of Alicyclic β-lactams via the Ugi Reaction
on a Solid Support
S.
Gedey, J. Van der Eycken and F. Fulop
Via the Ugi 4-centre 3-component reaction (U-4C-3CR), bicyclic cis-2-azetidinone derivatives were synthetised from cyclic β-amino acids on Super Acid Sensitive Resin (Sasrin). 2-, 3- or 4-Formylbenzoic acid was immobilised on the resin through its carboxy function. The U-4C-3CR was also carried out in solution, making use of scavenger resins for purification.
[Back to top] Intramolecular Azide Cycloaddition enroute to the
New Pyrrolo[2,1-c][1,2,3] triazolo[1,5-a][1,4]benzodiazepine Skeleton
G. Broggini, I. De Marchi, M. Martinelli, G. Paladino and A. Penoni
The unknown pyrrolo[2,1-c][1,2,3]triazolo[1,5-a][1,4]benzodiazepin-8-one ring system has been synthesised starting from the N-Boc-L-proline methyl ester. The totally diastereoselective intramolecular 1,3- dipolar cycloaddition of the azide 9 constitutes the key step of the synthetic sequence.
[Back to top] Re-Evaluation of a Solid-Phase Hydantoin Synthesis
Jesus Vazquez, Miriam Royo and Fernando Albericio
Solid-phase methods for the preparation of hydantoins are reviewed. Furthermore, an optimized method based on the concourse of 1,1’-carbonyldiimidazole allows the preparation of hydantoins without loss of chiral integrity.
[Back to top] Multivalent Recognition of Flavin Derivatives Using
Polymer Scaffolds
Joseph B. Carroll, Mark Gray, Kevin M. Bardon, Hiroshi Nakade and Vincent M. Rotello
Random copolymers of polystyrene were functionalized with diamidopyridine and anthracene recognition elements. Cooperative recognition between isobutyl flavin "guest" molecules and mixed recognition unit modified "host" copolymers was observed arising from a combination of aromatic stacking and hydrogen bonding interactions.
[Back to top] Synthesis of Luminescent N-Arylcarbazoles by Copper
Bronze-Mediated Reaction
M. Martinez-Palau, E. Perea, F. Lopez-Calahorra and D. Velasco
A copper bronze-mediated carbazole arylation reaction under mild reaction conditions is reported. Yields of 9-arylcarbazoles achieved are nearly quantitative and almost independent of the nature of the substitution on the carbazole or the aryl halide. A series of 9-arylcarbazole derivatives have been synthesized and their luminescence studied.
[Back to top] Synthesis of Boronated Alkoxyphenylalanines
A. Wolan, A. Laczynska, Z. Rafinski and M. Zaidlewicz
Synthesis of (2-methoxy-5-dihydroxyborylphenyl)alanine, (2-butoxy-5-dihydroxyborylphenyl) alanine, and (2-methoxy-4-dihydroxyborylphenyl)alanine for Boron Neutron Capture Therapy is described. In the key step, the amino acid functionality was introduced by the Wittig reaction. The approach provides a general access to alkoxy substituted boronated phenylalanines.
[Back to top] Synthesis of Enol Adenosine 5'-Phosphate Derivatives by
the Perkow Reaction of a Silylated Adenosine 5'-Phosphonate Derivative with
α-Halo Ketones
Tomohisa Moriguchi, Kazuhisa Okada, Kohji Seio and Mitsuo Sekine
This paper deals with the synthesis of α-substituted enol ester derivatives of adenosine 5’-phosphate. These compounds were formed by the Perkow reaction of α-chloromethyl ketones with an in situgenerated adenosine-5'-yl bis(trimethylsilyl) phosphite intermediate. Among these reactions, the use of α- chloro-2',4'-difluoroacetophenone gave predominantly the enol phosphate derivative over the Arbuzov reaction product and the carbonyl adduct, which were formed as byproducts.
[Back to top] Chiral Linker 1. A Novel Chiral Auxiliary Derived from m-Hydrobenzoin
as Enantiomerically Pure Linker for Solid Phase Organic Chemistry
P. Gaertner, C. Schuster and M. Knollmueller
The synthesis and utility of a novel, m-hydrobenzoin derived chiral auxiliary in stereoselective α-alkylation reactions using convenient solution chemistry as well as the attachment of an analogous system onto a solid support and its application as a dual chiral auxiliary and linker is described.
[Back to top] Chemoenzymatic Approach to a (R)-3,
4-Diaminobutanoic Acid Derivative with a Suitable Orthogonal Protection for
Solid Phase Peptide Synthesis
Monica Lopez-Garcia, Ignacio Alfonso and Vicente Gotor
The efficient chemoenzymatic synthesis of a (R)-3,4-diaminobutanoic acid derivative has been achieved. The final compound has suitable orthogonal protection for solid phase peptide synthesis.
[Back to top] Further Advances in the Synthesis of
α,β’-Difunctionalised Pyrroles
Severine Hebbe and Luc Dechoux
The reactivity of pyrrololactone 3 towards reductive and alkylating agents has been studied and the synthesis of diverse α, β’-difunctionalised pyrroles is presented. The ambivalent reactivity of compound 3 towards the different nucleophilic reagents has been rationalised.
[Back to top] Efficient Synthesis of Octahydro-5H-Dibenz[b,f]azepin-10-one
Derivatives by an Easy Two-Step Route from Available 2-Carbethoxymethyl
Cyclohexanone and Anilines
Alirio
Palma, Jacqueline Jaimes Barajas, Vladimir V. Kouznetsov, Elena Stashenko, Ali
Bahsas and Juan Amaro-Luis
Synthesis of new octahydrodibenz[b,f]azepin-10-one derivatives by a two-step synthetic route based on 2-carbethoxymethyl cyclohexanone reactivity is reported.
[Back to top] Mild and Most Efficient Silylcyanation of Aldehydes
Catalyzed by Cesium Fluoride
Sung
Soo Kim and Dae Ho Song
Cesium fluoride (CsF) catalyzes the addition of trimethylsilyl cyanide (TMSCN) to various aldehydes. Aromatic, aliphatic, cyclic and heterocyclic aldehydes have been converted into the corresponding trimethylsilyl ethers. Most of the aldehydes show over 99% yield for 20min. The mechanism of silylcyanation has been proposed.
[Back to top] Highly Diastereoselective Methylation of Five-Ring N,O-Acetals
Martin
Brunner, Thomas Straub, Pauli Saarenketo, Kari Rissanen and Ari M. P. Koskinen
Highly diastereoselective methylation of (2S,4S)- and (2R,4S)-3-tert-butyl 4-methyl 2-tertbutyloxazolidine-3,4-dicarboxylate (1a/b) is reported. The relative and absolute configuration of the methylated products was assigned by NOESY and confirmed by a crystal structure of 1a.
[Back to top] The First Dye-sensitized Photooxygenation of 2-(C-glycosyl)furans.
One-Pot Stereoselective Approach to New Carbohydrate Derivatives
Flavio
Cermola, M. Rosaria Iesce and Stefania Montella
The singlet oxygen oxygenation of 2-(α-C-glucopyranosyl)furans 1 leads readily and diastereoselectivity to the corresponding endoperoxides 2 whose fate can be controlled. Compounds 2 thermally rearrange into cis-dicarbonyl-α-O-glucosides 3 while by reduction they afford the cis-C-analogs 5. The latter readily convert to trans-8, which by silica gel chromatography tautomerize into β-anomers 9.
[Back to top] A Facile Synthesis of Dibenzylated p-tert-Butylcalix[4]Crowns
Under Non-Diluted Reaction Conditions
The straightforward synthesis of calix[4]crown derivatives in excellent yields under non-diluted reaction conditions is described. The reactions proceed smoothly at ordinary temperature and substrate concentrations of up to 1 M. Theoretical calculations on the reaction intermediates indicate that preorganization originating from the coordination of oxygen atoms to sodium ions plays an important role in the reaction.
[Back to top] Collapse and Self-Reconstruction of Mesoscopic
Architectures of Supramolecular J Aggregates in Solution: From Strings to
Tubular Rods
Hiroshi Yao, Chris A. Michaels, Stephan J. Stranick, Takeshi Isohashi and Keisaku Kimura
This Letter reports the collapse and subsequent self-reassembly of mesoscopic architectures of supramolecular J aggregates in solution. Ultrasonication of the string-like 5,5'-dichloro-3,3'-disulfopropyl thiacyanine (TC) J aggregates caused fragmentation (collapse) of the initial morphology, followed by a prompt self-reconstruction into mesoscopic rod-like architectures. Fluorescence microscopy, polarized light microscopy, atomic force microscopy and near-field scanning optical microscopy revealed that the apparent rod-like morphology was a tubular architecture with a monomolecular wall (single-wall) and open ends.